| Jet generating device and electronic apparatus -> Monitor Keywords |
|
|
 
Jet generating device and electronic apparatusRelated Patent Categories: Pumps, Motor Driven, Electric Or Magnetic Motor, Collapsible Wall Pump, Diaphragm Type, Piezoelectric DrivenJet generating device and electronic apparatus description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060239844, Jet generating device and electronic apparatus. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCES TO RELATED APPLICATIONS [0001] The present invention contains subject matter related to Japanese Patent Application JP 2005-123656 filed in the Japanese Patent Office on Apr. 21, 2005, the entire contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a vibrator for vibrating gas for generating a jet of the gas, a jet generating device including the vibrator, and an electronic apparatus including the jet generating device. [0004] 2. Description of the Related Art [0005] An increase in the scale and speed of large scale integrated circuits (LSI circuits) in recent years have caused electrical power consumption of the LSI circuits to increase year after year. Since most of the electrical power consumed by the LSI circuits is converted into heat energy, the increase in electrical power consumption has led to an increase in the heat value of the LSI circuits. With regard to a system using such an LSI circuit having high electrical power consumption, effort is being made to increase performance of a heat-dissipating system so that the temperature of the LSI circuit does not exceed its maximum operating temperature. [0006] The most general index indicating the performance of a heat-dissipating system is heat resistance. When the temperature of a heat source whose heat value is P[W] is T (.degree. C. or K) as a result of being cooled by a certain heat-dissipating system, a heat resistance Rth[K/W] of the heat-dissipating system is expressed by the following formula: Rth=(T-Ta)/P Here, Ta is ambient temperature (outside air temperature) when is an air-cooling system is used. In order not to increase the temperature of the heat source even if the heat value is high, the heat resistance of the heat-dissipating system is made small. In other words, a heat-dissipating system providing good performance is one having a small heat resistance. For example, in order for a maximum heat value to maintain the temperature of a 20[W] LSI circuit equal to or less than 70.degree. C., under an environment in which the outside air temperature has a maximum value of 40.degree. C., a heat-dissipating system having a heat resistance of less than 1.5 [K/W] is used. When the heat value of the LSI circuit is increased to 100 [W], a typical heat resistance is less than 0.3 [K/W]. [0007] A heat-dissipating system which makes use of forceful air cooling basically includes a heat exchanger exchanging heat between a heat source and outside air and an air blower which sends the outside air to the heat exchanger. The heat resistance of this heat-dissipating system may be reduced by increasing efficiency of the heat exchanger or by increasing an air discharge amount of the air blower. For example, by putting thought in the material and structure of a radiating fin or by increasing the surface area of the radiating fin, the efficiency of the heat exchange can be increased. In a system using an axial fan which rotates as the air blower, the air discharge amount can be increased by, for example, increasing the rotational speed or diameter of the fan. [0008] However, in forceful convection of air with such a fan, a temperature boundary layer at a surface of the fin is produced at a downstream side of the fin, thereby giving rise to the problem that heat from the radiating fin is not efficiently removed. This problem may be solved by, for example, reducing the thickness of the temperature boundary layer as a result of increasing fan air velocity. However, increasing the rotational speed of the fan for the purpose of increasing the fan air velocity causes noise to be generated, such as noise from a fan bearing or noise of the wind produced by the fan. [0009] Methods using a vibrating plate that reciprocates periodically (refer to, for example, Japanese Unexamined Patent Application Publication Nos. 2000-223871 (FIG. 2), 2000-114760 (FIG. 1), 2-213200 (FIG. 1), and 3-116961 (FIGS. 3 and 11)) are available as methods which efficiently allow heat from a radiating fin to escape to outside air by destroying the temperature boundary layer without using a fan as an air blower. Of devices in these four documents, in particular, the devices in Japanese Unexamined Patent Application Publication Nos. 2-213200 and 3-116961 include a vibrating plate which roughly divides space in a chamber in two, a resilient member disposed in the chamber and supporting the vibrating plate, and a unit which vibrates the vibrating plate. In these devices, for example, when the vibrating plate is displaced upwards, the volume of an upper space of the chamber is reduced. Therefore, the pressure in the upper space is increased. Since the upper space is connected to the outside air through a suction-exhaust opening, a portion of the air in the upper space is discharged to the outside air by the pressure increase in the upper space. At this time, the volume of a lower space that is opposite to the upper space (the vibrating plate is disposed between the lower space and the upper space) is increased, causing the pressure in the lower space to decrease. Since the lower space is connected to the outside air through a suction-exhaust opening, the pressure reduction in the lower space causes a portion of the outside air existing near the suction-exhaust opening to be sucked into the lower space. In contrast, when the vibrating plate is displaced downwards, the volume of the upper space of the chamber is increased. Therefore, the pressure in the upper space is decreased. Since the upper space is connected to the outside air through the suction-exhaust opening, the pressure reduction in the upper space causes a portion of the outside air existing near the suction-exhaust opening to be sucked into the upper space. At this time, the volume of the lower space that is opposite to the upper space (the vibrating plate is disposed between the lower space and the upper space as mentioned above) is decreased, causing the pressure in the lower space to increase. The pressure increase in the lower space causes a portion of the air in the lower space to be discharged to the outside air. The vibrating plate is driven by, for example, an electromagnetic driving method. Accordingly, by reciprocating the vibrating plate, the discharging of the air in the chamber to the outside air and the sucking of the outside air into the chamber are periodically repeated. Pulsating air induced by a periodic reciprocating movement of the vibrating plate is blown against a heating element such as the radiating fin, so that the temperature boundary layer at the surface of the radiating fin is efficiently broken, as a result of which the radiating fin is cooled with high efficiency. SUMMARY OF THE INVENTION [0010] In a device using a vibrating plate which reciprocates, such as the devices in the aforementioned four documents, in principle, an air discharge amount can be increased by increasing the area or vibration amplitude of the vibrating plate. However, when the size (volume) of the device is limited, such as when a heating element in a small apparatus is cooled, there is a limit as to how large the area or the vibration amplitude of the vibrating plate can be made. In addition, increasing the area or the vibration amplitude of the vibrating plate increases electrical power consumption of the device. [0011] In, for example, Japanese Unexamined Patent Application Publication No. 2-213200, a driving frequency of the vibrating plate is in a non-audible area of approximately 10 Hz. In Japanese Unexamined Patent Application Publication No. 3-116961, the air velocity in front of the radiating fin differs depending upon the frequency of the vibrating plate, with the air velocity being greater at 19 Hz than at 15 Hz (lower right column on page 3 of the specification). However, when the driving frequency is merely set at a lower non-audible area, noise is restricted, but an air discharge area per unit time is reduced in correspondence with the lower frequency. [0012] In view of the aforementioned problems, it is desirable to provide a jet generating device which can increase heat-dissipation capability while restricting electrical power consumption as a result of optimizing a driving frequency of a vibrating member, and an electronic apparatus including the jet generating device. [0013] According to an embodiment of the present invention, there is provided a jet generating device including a housing having an opening and containing gas therein, a vibrating member which is supported by the housing so that the vibrating member is capable of vibrating and which vibrates the gas to discharge the gas as pulsating gas through the opening, a driving mechanism for driving the vibrating member in accordance with an electrical signal, and a drive controller which generates the electrical signal at a fundamental frequency at which an input impedance of the driving mechanism is substantially a maximum and which outputs the generated electrical signal to the driving mechanism. [0014] When the vibrating member is driven at a frequency near the fundamental frequency at which the input impedance is a substantially maximum value, heat resistance when a heating element is subjected to heat dissipation is a minimum value. In other words, the inventor has found out that, the frequency when the heat resistance is a minimum value matches the frequency at which the input impedance of the driving mechanism is substantially a maximum. The smaller the heat resistance, the higher the performance of the jet generating device. Therefore, according to the embodiment of the present invention, it is possible to provide a maximum heat-dissipation capability with minimum electrical power consumption. [0015] A driving method of the driving unit may make use of, for example, an electromagnetic action, a piezoelectric action, or an electrostatic action. [0016] The type of gas which may be used is not only air, but also nitrogen, helium gas, argon gas, or other types of gas. [0017] The vibrating member may have a three-dimensional structure instead of a structure having a flat-plate form. For example, the vibrating plate may have a structure in which, for example, a side plate or a rib is mounted to the vibrating plate in order to increase rigidity. However, the vibrating member may have any form which is not limited to such a purpose. In addition, the shape of the vibrating member in a plane perpendicular to the direction of vibration of the vibrating member may be, for example, circular, elliptical, or rectangular. [0018] In one form, the drive controller sets the fundamental frequency lower than a minimum resonance frequency of the vibrating member. For a high frequency range where a sound pressure level of the vibrating member is low (that is, a frequency range which is sufficiently higher than a minimum resonance frequency), the input impedance may become greater than the aforementioned maximum value. Accordingly, the vibrating member may be driven at such a high frequency range. In such a case, the vibration amplitude of the vibrating member becomes extremely small. This may make it impossible to obtain a predetermined gas discharge amount. In contrast, in a low frequency range near the minimum resonance frequency, even if electrical power is the same as when the vibrating member is driven at the high frequency range, the vibration amplitude can be set at its maximum value, so that, according to the embodiment of the present invention, the fundamental frequency is set near the minimum resonance frequency of the vibrating member. [0019] In still another form, more specifically, the drive controller includes an amplifier and a signal generator, the signal generator generating a sinusoidal signal, a voltage pulse signal, or an electrical current pulse signal, each signal having a fundamental frequency at which an input impedance of the amplifier is substantially a maximum, the amplifier amplifying the generated signal and outputting the amplified signal to the driving mechanism. In this case, it is desirable that the signal generator be such that a total harmonic distortion factor of the electrical signal is less than 10%. By setting the harmonic distortion factor at a value which is less than 10%, a harmonic component providing high auditory sensation characteristics is reduced, so that the noise is at a level that does not bother human beings. [0020] According to another embodiment of the present invention, there is provided an electronic apparatus including a heating element, a housing having an opening and containing gas therein, a vibrating member which is supported by the housing so that the vibrating member is capable of vibrating and which vibrates the gas to discharge the gas as pulsating gas towards the heating element through the opening, a driving mechanism for driving the vibrating member in accordance with an electrical signal, and a drive controller which generates the electrical signal at a frequency range including a fundamental frequency at which an input impedance of the driving mechanism is substantially a maximum and which outputs the generated electrical signal to the driving mechanism. [0021] Examples of the electronic apparatus are a computer (which may be a laptop computer or a desktop computer when the computer is a personal computer), a Personal Digital Assistance (PDA), an electronic dictionary, a camera, a display device, an audio/visual device, a cellular phone, a game device, a car navigator system, a robot apparatus, and other electronic products. Continue reading about Jet generating device and electronic apparatus... Full patent description for Jet generating device and electronic apparatus Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Jet generating device and electronic apparatus patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Jet generating device and electronic apparatus or other areas of interest. ### Previous Patent Application: Electric compressor Next Patent Application: Pump Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Jet generating device and electronic apparatus patent info. IP-related news and info Results in 0.49663 seconds Other interesting Feshpatents.com categories: Medical: Surgery , Surgery(2) , Surgery(3) , Drug , Drug(2) , Prosthesis , Dentistry 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
